Operand liveness state information is maintained during context switches for current architected operands of executing programs the current operand state information indicating whether corresponding current operands are any one of enabled or disabled for use by a first program module, the first program module comprising machine instructions of an instruction set architecture (ISA) for disabling current architected operands, wherein a current operand is accessed by a machine instruction of said first program module, the accessing comprising using the current operand state information to determine whether a previously stored current operand value is accessible by the first program module.